1. Field of Invention
The present invention relates, in general, to a shift control method for a dual clutch transmission (DCT) vehicle and, more particularly, to a technique for making it possible to secure fast shift responsiveness according to vehicle operation of a driver.
2. Description of Related Art
Dual clutch transmissions (DCTs) are designed to provide two input shafts connected to two respective clutches, to dispose shift stage gears installed on the two input shafts with the shift stage gears divided into odd and even number sides, and to functionally distinguish the two input shafts such that one of the two shafts is used for the odd number stages and the other is used for the even number stages.
Thus, the DCTs configured as described above have an advantage in that, when an arbitrary shift stage is changed to the next shift stage, the clutch connected to one input shaft for the current shift stage is disengaged, and the clutch connected to the other input shaft for the next shift stage is engaged, so that gears can be changed while torque transmitted to driving wheels in changing gear is prevented from being completely interrupted.
However, in the DCTs, a change between the shift stages disposed at the same input shaft is impossible in the way as described above. Thus, the current shift stage of the same input shaft should be changed to the shift stage of the other input shaft, and then to the other shift stage of the input shaft at which the current shift stage is again disposed.
For example, a DCT is assembled such that the input shaft for the odd number stages realizes odd number stages of first to seventh stages and that the input shaft for the even number stages realizes even number stages of second to sixth stages. When the current seventh stage, during traveling, is to be changed to the fifth stage disposed on the same input shaft, the current seventh stage should be primarily changed to the sixth stage of the even number stage input shaft, and then to the fifth stage again.
However, during the traveling of a vehicle, there occurs a need for sudden shift from the current shift stage to one of the two or more other shift stages higher or lower, rather than sequential shift. This occurs when a driver suddenly accelerates or abruptly enters an uphill incline. In this situation, the sequential shift as described above should be continuously performed several times. In this case, it takes much time to change gear, and a time for which torque is not smoothly transmitted to the driving wheels is increased. This may affect acceleration and shift performance of the vehicle, thus causing discomfort to the driver.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.